Objective: ACE is the key enzyme of renin-angiotension-aldosterone system(RAAS). The insertion (I allele) deletion (D allele) polymorphism of ACE gene determines the serum level of ACE. There are three genotypes including DD, ID and II. The aim of this study was to study the possible impact of this polymorphism on risk of renal function decline in Chinese elderly people. Methods: A total of 366 elderly patients from geriatrics department of Ruijin Hospital in 2010 was enrolled. Medical history (hypertension and diabetes) was collected, weight and the basic clinical characteristics were measured. Polymerase chain reaction (PCR) was used to determine the ACE genotypes (ID, II, DD). Patients were followed up in 2011 and 2016. After excluding the dead and those lost to follow-up, 152 cases were remained for analysis. These patients were divided into two groups according to the ACE genotypes, the group DD+ID and the group II. Results: Retrospective analysis showed that the 6 years follow-up demonstrated a trend of decline of weight and creatinine clearance rate(Ccr)(P<0.05) and a trend of rising of fast blood glucose level(P<0.05). There were no significant differences in fast blood lipid level, the incidence of diabetes and hypertension(P>0.05). There were no significant differences between group DD+ID and group II for weight, sex, age, fast blood glucose level, fast blood lipid level, incidence of diabetes and hypertension (P>0.05). Group DD+ID had more decline of Ccr than group II(P<0.05). Conclusions: The D allele of ACE gene is a risk factor of decline of kidney function in Chinese elderly people.